Detachable core pin with elongated hollow space



Jan. 29, 1963 R. v. STUMPH ETAL 3,075,265

DETACHABLE CORE PIN WITH ELONGATED HOLLOW SPACE Filed NOV. 2, 1960 j. IIQVENTORS za/g H TTOE/VE) United States Patent 3,075,265 DETACHABLE CORE PIN WITH ELONGATED HOLLOW SPACE Richard V. Stumph and Harry A. Williamson, Bedford, Ind., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Nov. 2, 1960, Ser. No. 66,756 4 Claims. (Cl. 22-152) This invention relates to permanent-type metal casting molds and more particularly to permanent molds such as die casting dies having a core pin extending into'the cavity thereof.

The casting in permanent molds,[such as die casting dies, of articles having openings such as bolt holes and the like therein is generally accomplished by providing molds or dies which have a permanentcore protruding or extending into the die cavity. Typically, the core extends from a point at the outside surface of the mold where it is fastened to the die, through a passage in the mold and into the mold cavity as required by the article to be cast therein. In die casting apparatus, the die is mounted on a die plate or block so that the point at which the core pin is anchored or fastened is located between the die plate and the die. In the operation of die casting equipment, it is common for the portion of the core pin extending into the die cavity to be sheared flush with the surface of the die cavity, usually in the process of removing the casting from the die cavity. When this occurs, it is then necessary to disassemble the die from the die plate of the die casting apparatus and to replace the core pin from the rear side of the die.

It is the basic object of this invention to provide a mold or die structure including a core pin projecting into the die cavity in which the portion of the core pin projecting into the die cavity may be easily and efliciently removed and replaced from the cavity side of the die. It is a further object of this invention to provide a core pin adapted for insertion Within a mold or die body and having a core end portion which may be readily detached from the base portion of the core pin from the mold cavity side after it has been sheared flush with the die cavity wall.

These and other objects of the invention are accomplished by providing a moreor less conventional die or mold adapted to be fastened to a die plate or the like having a mold cavity and a passage therethrough adapted to receive a core pin which extends from a surface thereof adjacent the die plate to a point within the die cavity. A core pin is provided which consists essentially of a forward core portion and a rear or base portion which are detachably secured to one another in aligned relation as, for example, by thread means. Preferably, the parts are fastened together by providing the base portion with a stud and threading an opening within the forward portion whereby the parts may be threadably attached to one another. An essential feature of the invention involves the provision of a longitudinally elongated internal passage or void within the forward portion which extends from the stud to a point within the portion of the core to be located within the die cavity.

Other objects and advantages of this invention will more fully appear from the following detailed description of a preferred embodiment thereof, reference being made to the drawings wherein:

FIGURE 1 is a view in partial cross section of a twopart core pin constructed in accordance with this inven tion;

FIGURE 2 is a fragmentary view of die casting dies showing the core pin of FIGURE 1 positioned therein; and

FIGURE 3 is a partial cross'section of die casting apparatus showing the core pin sheared at the die cavity face being removed in accordance with this' invention.

Referring now to the drawings the core pin of themesent' invention is associated with diecasting apparatus of more or less conventional construction; As shown in FIGURE 1, the core pin 10 consists of a base'portion 11 having a head or flanged end 12 and an opposite end 14 of reduced diameter which is provided with external threads to form a stud and a forward core' portion 16.

The forward portion 16 is provided with an opening 18 therein which extends well into the po rtion of the core pin which is to project into'the diecavity. The rearmost portion 20 of the opening 118 is formed and threaded portion 11 or plate 22 by'a'suitable number of screws or bolts. A mov able die 28 is: fastened to the movable die plate 24 by a suitable number of screws or bolts (not shown); The adjacent faces of the opposed dies 26 and 28 are contoured to define between them the die cavity 30 which communicates with a sprue 34 located in the stationary die 26. A molten metal injection nozzle 36 engages the sprue 34' influid flow relationship. A gas heating means 32 is preferably provided about the nozzle 36 to prevent molten metal from solidifying therein.

It isto be understood, of course, that the die plate 24 is to'be moved to and. away from the die plate 22 in the opening and closing of the die members and in order that the dies 26 and 28 register properly as they approach each other, locating pinsor dowels (not shown), may be carried by the die members as is well known'in the art.

The ejecting mechanism by which castings formed in the cavity 30 are dislodged from the dies includes an ejector plate 38 located in a space 39 provided within the die plate 24; Ejecting pins 40 are secured to the ejector-plate 38 by means of plates 41 screwed thereto and extend through bores'provided in the movabledie member 28. When the diesare in condition to-receive a charge of molten metal, the forward ends of these pins are substantially flush with the exposed surface of the movable die member. The retraction of the ejecting pins to bring about this condition is effected by hydraulically actuated push rods 42 fastened to the ejector plate 3-8 and guided through bores 43 of the die plate 24. When the dies are in the position shown in FIGURE 2, the dies are closed and the ejector pins are retracted so that they are in a casting position.

When the die plate 24 and the parts carried thereby are retracted to open the dies, the actuators or plungers 42 which are slidably supported by the die plate 24 engage a stationary abutment (not shown) to cause the ejector plate 38 to move in a direction opposite to the movement of the movable die 24. This causes a like action of the ejector pins 40 and it is this action which causes the casting to be dislodged from the movable die member 28.

A feature of this invention which distinguishes it from conventional die casting apparatus is the core pin 10 which extends through a bore or passage in the movable die 28 and into the cast-ing cavity 30. Preferably the core pin 10 has a flanged base portion 12 as above described which is received in a countersunk opening of the movable die 28 and is clamped between the movable plate 28 and the movable die plate 24 whereby the core pin 10 is firmly fixed with respect to the movable die 28. Preferably the flanged base portion 12 is keyed or otherwise non-rotatably secured within the countersunk opening of the movable die 28. This is necessary so that the forward.

portion 16 of the core pin may be unscrewed from the base portion 11 as will appear hereinafter. The core portion 19 of the core pin extends into the casting cavity 3i). To mount the core pin 10 in the die 28 initially, it is necessary to disassemble the movable die 28 from the movable plate 24 in an obvious manner. It is to be noted that the opening 18 in the core pin extends from a point well within the body of the movable die 28 to a point well within the portion 19 of the core pin which extends into the die cavity 30.

As previously pointed out, it frequently happens that in the operation of die casting apparatus the portion 19 of the core pin which extends into the die cavity and functions as a core is sheared off at the face of the die cavity 44 as shown in FIGURE 3. In the past, when this happened, it was necessary to remove the movable die 28 from the movable plate 24 to replace the core pin 10. To repair the core pin of the present invention, it is only necessary to insert a suitable instrument such as an easy-out tool 46 into the opening 18 of the core pin which has been exposed by reason of the portion 19 of the core pin being sheared off, to unscrew the remaining portion of the forward portion 16 from the stud portion 14 and to screw another forward core pin portion 16 over the stud 14. Since this operation is performed from the cavity side of the die, the replacement operation involves no disassembly of the apparatus and is penformed simply and expeditiously. 7

While the invention has been described by means of a specific embodiment, it will be understood that the scope is not limited thereby except as defined in the following claims.

We claim: I

1. A mold construction comprising a mold body having a casting cavity and a core pin, said core pin being positione d within a passage through said mold body and extending into said cavity, said core pin comprising two sections detachably fastened to one another within said mold body, one of said sections snugly engaging the walls of saidpassage projecting into said mold-cavity and having'an elongated space therein extending from a point within said mold cavity to a point within the mold body, said space being adapted to receive an easy-out tool by which said section projecting into said mold cavity maybe detached from the other section when the said projecting portion has been sheared substantially at the mold face.

2. A core pin for use in permanent molds comprising a base'portion and a core portion detachably secured to one another in an aligned relation, said base portion having transversely extending means for securing the core pin in a mold, said core portion having an elongated hollow space therein adapted to extend from a point within the mold body to a point within the mold cavity when the core pin is associated with a mold said core. portion having a cylindrical section adapted to engage the said mold body. s

3. A mold comprising a mold body adapted to be mounted on a die plate having a casting cavity on one side thereof, a rear side adapted to face the said die plate and a core-pin disposed within a passage extending through said core body, said core pin comprising a first and second section threadably attached to one another within said passage, said first section being attached to said body at said rear side, said second section snugly engaging the wall of said passage and being projected into said moid cavity and having an elongated space therein extending from a point within said mold cavity to a point within the mold body, said space being adapted to receive an easy-out tool whereby'said second section may be detached from said first section when the former has been sheared substantially at the mold face. 7 V

4. A mold comprising a mold body adapted for mounting on a die plate having a casting cavity on one side thereof, an oppositely disposed rear side adapted to face the said die plate and a core pin snugly disposed within a cylindrical passageextending through said mold body, said core'pin comprising a first section and a second section detachably fastened to one anotherwithin said passage, said first section being mounted at the rear face of said body, saidfsecoud section snugly engaging said passage wall and'being projectedinto said mold cavity, said second section having an elongatedspace therein extending from a point within said mold cavity to a point within the mold body,,said space being adapted to receive an easyout tool whereby said second section may be detached'from the first .section whenthe former has been sheared ofi' substantially at the moldfc'avity surface.

References pi ted inthefile of this patent 1 UNITED STATES PATENTS 2,602,190 Hein'et a1 July 8, 1952 

2. A CORE PIN FOR USE IN PERMANENT MOLDS COMPRISING A BASE PORTION AND A CORE PORTION DETACHABLY SECURED TO ONE ANOTHER IN AN ALIGNED RELATION, SAID BASE PORTION HAVING TRANSVERSELY EXTENDING MEANS FOR SECURING THE CORE PIN IN A MOLD, SAID CORE PORTION HAVING AN ELONGATED HOLLOW SPACE THEREIN ADAPTED TO EXTEND FROM A POINT WITHIN THE MOLD BODY TO A POINT WITHIN THE MOLD CAVITY WHEN THE CORE PIN IS ASSOCIATED WITH A MOLD SAID CORE PORTION HAVING A CYLINDRICAL SECTION ADAPTED TO ENGAGE THE SAID MOLD BODY. 